Candida albicans specializations for iron homeostasis: from commensalism to virulence

• The yeast C. albicans is a commensal and pathogen of humans and other mammals.
• Iron and zinc are sequestered in mammalian blood and tissues but not in the gut.
• C. albicans virulence requires specialized mechanisms for acquiring host iron and zinc.
• Limitation of iron uptake promotes C. albicans commensalism in the gut.

Candida albicans is a fungal commensal-pathogen that persistently associates with its mammalian hosts. Between the commensal and pathogenic lifestyles, this microorganism inhabits host niches that differ markedly in the levels of bioavailable iron. A number of recent studies have exposed C. albicans specializations for acquiring iron from specific host molecules in regions where iron is scarce, while also defending against iron-related toxicity in regions where iron occurs in surfeit. Together, these results point to a central role for iron homeostasis in the evolution of this important human pathogen.